On account of their high specific power, electronically commutated motors, or brushless motors, can be used to control the rotation of a mechanical member in a large number of applications.
Rotating motors are typically controlled by a motor drive that receives a desired motor speed signal and, based on the motor speed signal, produces and outputs a torque signal that is applied to the motor. Adjustment of the torque signal based on changes to the desired motor speed signal relative to the actual motor speed ensures that the motor rotates at the desired speed. However, when operating a plurality motors synchronously in an automated system, several factors exist that may cause the position of the motors to deviate from each other even though they are all operating under the same desired motor speed signal. For instance, motor inertia and other losses at each motor are non-uniform, and could cause one motor to drift from the other motors. Many automated control systems implement a position feedback loop, whereby the position of each motor is compared to a desired motor position so that the torque output to each individual motor may be adjusted to compensate for motor drifting.
Accurate control of electric motor-based position systems requires accurate, low latency sampling of motor position signals. These position signals are typically need to be expressed in different forms depending upon the type of system eliciting position information. For example, low-rate control systems typically elicit absolute position signals. Other systems, such as, high-rate electronic control systems may elicit position outputs in the form of continuous incremental quadrature signals. However, commercial-off-the-shelf electronic systems do not typically provide this type of data in different formats with the required level of concurrency.